That is, video playback with anything: chrome (html 5), firefox (flash), vlc, totem, smplayer... whatever
It works only if the software is started as root otherwise it freezes at the begin
Interesting enough, in chrome, you can move the slider to whatever position and see the current frame updated
However the video stays stil
This started to happen a couple of days ago after an unidentified update
Relevant output from chrome run as normal user gives some hint:
NVIDIA: could not open the device file /dev/nvidia0
No output coming from firefox or vlc
$ ls -l /dev/nvidia0
crw-rw-rw- 1 root root 195, 0 nov 8 21:18 /dev/nvidia0